In July 1808 Paris wilted in a heatwave. The average maximum for the 13-day spell that began on the 10th was 31°C, higher than a similar spell last month that saw the all-time record for the French capital broken.
The temperature at the peak of last month’s hot spell reached 42.6°C, some 6.4°C higher than the peak of the 1808 spell but, as the graph below shows, maxima fell back more quickly than 1808.
The more ‘pointed’ nature of maximum temperature during the spell last month backs up findings of the changing jet stream; the wriggly nature amplifying the heat.
The average mean and minimum temperature of both spells showed a difference of just 0.2°C.
Since Paris recorded its hottest day ever there have been just two days where the temperature has exceeded 30°C.
The heat in Paris in 1808, like in 2019, was also felt in London. Luke Howard noted the following in The Climate of London.
“Very hot from July 12th to 19th. On the 12th a thermometer in perfect shade in a window in St James’s Park was 81.5 degrees at 3pm, and on the 13th at the same hour, 94 degrees. On the same day four men and seven women were killed by sunstroke in various parts of the Midland counties, and numerous coach and other horses were also killed. On the 15th a very violent and destructive thunderstorm in Gloucestershire, Monmouthshire, and surrounding counties.”
* Values for 2019 were taken from the station Montsouris.
** Though there is no way of knowing how accurate the 1808 values were previous studies have found that historic temperatures can be as much as 3°F too high.